Software Engineer: Platform and Backend (Mid-career / Senior)

Theia Insights; Cambridge; On-site; GBP 70,000 - 90,000; Full time

Benefits offered by this job

EMI share options

Private health insurance

Pension

25 days holiday + bank holidays

Hybrid work in UK (London orCambridge

Job summary

Theia Insights is seeking a mid-to-senior backend engineer in the UK to build scalable async REST endpoints using FastAPI and Python. You will manage large data pipelines with Pandas, Parquet/Arrow, and DuckDB, while owning identity and access via AWS IAM and OAuth2/OIDC.

Work closely with data teams to design new data access points, run services on AWS, and occasionally contribute to front-end features in TypeScript/React for end-to-end ownership and reliability.

Qualifications

• Production-level Python software with testing and observability.
• Experience delivering HTTP APIs in FastAPI or similar framework.
• Handling large tabular data with Pandas/Parquet/Arrow.

Responsibilities

• Build and operate async REST endpoints serving large datasets.
• Work with large tabular data using Pandas, Parquet/Arrow, and DuckDB.
• Own identity and access layer with AWS IAM, OAuth2/OIDC.

Skills

Python

FastAPI

Pandas

Parquet/Arrow

DuckDB

OAuth2/OIDC

REST APIs

TypeScript/React

AWS

RBAC

Tools

AWS CDK

Terraform

S3

CodePipeline

Job description

About the role

Theia Insights builds foundational financial intelligence products, including industry classification, knowledge graphs and factor risk models, for institutional investors. We serve some of the largest asset managers, hedge funds, index providers and sell-side banks.

What you’ll do

• Build and operate async REST endpoints (FastAPI, Pydantic) that serve large datasets reliably and quickly.
• Work with large tabular data in pandas, Parquet/Arrow and DuckDB, and manage the memory and performance trade-offs of moving big datasets efficiently.
• Own the identity and access layer, including AWS technologies for identity, authorisation and data distribution, supporting access to data through multiple channels.
• Design and build new access points for our data, such as APIs, analytical services and MCP connectors.
• Run services on AWS, with infrastructure in AWS CDK shipped via CodePipeline.
• Productionise code from the data and quantitative teams.
• Occasionally contribute changes to Theia Insights’ TypeScript/React frontends that consume our API, particularly where a feature is simplest to own end to end.
• Take end-to-end ownership of reliability and performance, including graceful handling of failure modes.
  Essential
• Strong production Python including experience shipping and operating services.
• HTTP APIs in a typed framework such as FastAPI, with schema and contract discipline.
• Production AWS: S3, a compute service (e.g. ECS/Fargate or Lambda) and a datastore, with least-privilege IAM.
  Useful
• Auth in production: OAuth2/OIDC, JWT validation, API keys, scopes.
• Tabular data at scale: pandas plus Parquet/Arrow, ideally DuckDB.
• Multi-tenant SaaS: RBAC, API-key management.
  Nice to have
• Infrastructure as code (CDK in TypeScript, or Terraform).
• React/TypeScript, or comfort in a polyglot repo.
• LLM or MCP integration and AI-facing tooling.
• Financial-data or regulated-environment background.

Experience we’re looking for

We care more about what you’ve owned than years on a CV. A strong mid-level engineer who has shipped and operated production AWS services, owning one end to end with tests, will meet the bar. Senior candidates will likely have designed large scale systems, owned responsibilities for auth or multi-tenant access, made cross-region and disaster-recovery trade-offs, and set the standard for a team.

• Competitive salary plus EMI share options
• 25 days holiday + bank holidays
• Private health insurance, pension
• Hybrid working in UK from London or Cambridge